1. Field of the Invention
The present invention relates to a control unit which performs position control or speed control through a use of a vibration type actuator.
2. Related Background Art
Generally, a vibration type actuator has a vibration member to be composed of an elastic member and a piezo-electric element as an electro-mechanical energy conversion element, and to the elastic member, the piezo-electric element has been bonded or bonded compressively at a position having a phase difference of 90xc2x0 each other in space, and a two-phase alternating signal having a phase difference is applied to the piezo-electric element, whereby a traveling wave is caused to be generated on the elastic member, a contact member (movable member) is brought into close contact with this traveling wave, and by a frictional force, the contact member is caused to relatively move to the vibration member. In this respect, onto a contact portion between the elastic member and the contact member, friction material for obtaining an appropriate frictional force is bonded, coated or formed.
As regards drive control of such a vibration type actuator, there have been proposed a system for controlling a driving frequency, a system for controlling the driving voltage, and a system for controlling a phase of the above-described two-phase alternating signal, and as disclosed in, for example, Japanese Patent Application Laid-Open No. 06-197566, there has been a system in which the frequency is controlled such that a phase difference between a vibration detection signal obtained at an element portion for vibration detection provided on the piezo-electric element and applied voltage which is one alternating signal for driving to be applied to the drive unit of the piezo-electric element becomes a predetermined value.
In such a control system, since the frequency of driving voltage has been set in response to a phase difference between the vibration detection signal and the applied voltage, the response is slow and it is not possible to improve response of vibration within a time period of one period or half period level of the driving voltage. Therefore, acceleration and deceleration thereof are slow and such system is vulnerable to abrupt load fluctuation, and when the driving frequency is in the vicinity of a resonance frequency, an abrupt stop may occur.
The present invention solves such conventional problems and provides a control unit for a vibration wave actuator for enabling quick-response and reliable control.
According to one aspect of the present invention, there is provided a vibration type actuator apparatus which excites a vibration member to obtain a driving force by applying each of plural phases of driving volage to respective different electro-mechanical energy conversion element portions for driving respectively, including: a detection circuit for forming a signal which indicates a periodic change in response to a vibration state of the vibration member; and a control circuit which controls timing in applying the driving voltage to the energy conversion element portion on the basis of timing of a periodic change in a detection output signal of the detection circuit concerned.
According to one aspect of the present invention, there is provided a vibration type actuator apparatus which excites a vibration member to obtain a driving force by applying each of plural phases of driving volage to respective different electro-mechanical energy conversion element portions for driving respectively, comprising: a detection circuit which detects vibration of the vibration member to form a signal having waveform corresponding to the vibration displacement; and a control circuit which applies the driving voltage to the energy conversion element portion with a phase shifted by a predetermined phase from signal waveform from the detection circuit concerned.
According to one aspect of the present invention, there is provided a vibration type actuator apparatus which excites a vibration member to obtain a driving force by applying each of plural phases of driving volage to respective different electro-mechanical energy conversion element portions for driving respectively, comprising a circuit which determines timing with which the vibration member is excited in accordance with timing of vibration displacement of the vibration member.
According to one aspect of the present invention, there is provided a method of driving a vibration type actuator apparatus which excites a vibration member to obtain a driving force by applying each of plural phases of driving volage to respective different electro-mechanical energy conversion element portions for driving respectively, including the steps of: detecting vibration of the vibration member to form a signal indicating a periodic change in response to a state of vibration; and controlling timing in applying the driving voltage to the energy conversion element portion on the basis of timing of a periodic change of the signal concerned.
According to one aspect of the present invention, there is provided a method of driving a vibration type actuator apparatus which excites a vibration member to obtain a driving force by applying each of plural phases of driving volage to respective different electro-mechanical energy conversion element portions for driving respectively, including the step of: determining timing with which the vibration member is excited in accordance with timing of vibration displacement of the vibration member.
Other objects of the present invention will become more apparent from the following description of embodiments taken in conjunction with the accompanying drawings.